Scribing instruments



July 30, 1968 c. H STEIN ET AL 3,394,460

SCRIBI'NG INSTRUMENTS Original Filed April 20, 1961 FIG. I

79 FIGS 79 //4 INVENTOR CHARLES STEIN FIG.7 W LIAM KRAUSE BY W ATTORBE+ AGENT United States Patent 11 Claims. (Cl. 33-27 ABSTRACT OF THE DISCLOSURE A device for scribing two concentric circles with a single compass-like instrument having a pointed center shaft with a tubular scriber rotatably mounted thereon with the tubular scriber having a cutting edge adapted to make a very small circle and the compass having a second scriber spaced from the center shaft to make a larger diameter circle with both scribers having cutting points to scribe concentric circles through a peelable layer whereby the annular portion of peelable material between the concentric circles may be removed as a unit, the invention being particularly useful for making printed circuits for electronic purposes by use of a photographic method.

The present application is a division of application Ser. No. 443,743, filed Mar. 1, 1965, which has resulted in Patent No. 3,271,862, issued Sept. 13, 1966, which was a division of application Ser. No. 104,482, filed Apr. 20, 1961, which issued as Patent No. 3,197,871 011 Aug. 3, 1965, which was a continuation-in-part of application Ser. No. 817,852, filed June 3, 1959, now abandoned.

The present invention relates to instruments for making master templates for cartography circuit cards and the like Where accurate duplications are essential for accurate registry in maps and to obtain constant electrical characteristics in duplicate circuit cards including constant resistance of conductors and constant capacitance between adjacent conductors in each completed circuit card.

Heretofore scribing and cutting instruments of many different designs which usually had a single scribing or cutting edge have been used but the lines and cuts have been coarse and irregular and the edges of the outlined areas have not been parallel and even with a photographic reduction step in the process the reproductions particularly in circuit cards have had objectionable variations in the sizes of the conductors with resulting inaccuracies in the circuits. Also, the previous method of production of a circuit card master with the heretofore known instruments involved many delays.

An object of the present invention is to provide means and method to obtain accurate reproductions in cartography and in circuit cards with a minimum of variation and a minimum of skilled personnel.

Another object is to provide scribing and cutting instruments which trace the pattern for circuit cards.

Another object is to provide instruments for obtaining scribing and/or cutting of two lines in one operation.

Another object is to provide methods of producing accurate masters for graphic arts.

A further object is to provide a method of making a finished circuit card involving a master pattern or template from which the circuit card is duplicated.

Other and further objects will be apparent as the description proceeds and upon reference to the accompanying drawings, wherein:

FIGURE 1 is a front elevation with parts broken away of a circle cutting device in the form of a drop type bow compass with a tubular cutter slidably mounted on the 3,394,460 Patented July 30, 1968 drop center and a chisel ty-pe cutter substituted for the circle scribing element.

FIGURE 2 is an enlarged section of the tubular cutter taken substantiallyon line 2-2 of FIGURE 1 showing the drop center projecting through the tubular cutter.

FIGURE 3 is a similar enlarged section through the tubular cutter and the lower portion of the hollow center of the bow compass with the point of the drop center in normal retracted position in the tubular cutter.

FIGURE 4 is an enlarged side elevation of the chisel type outer circle cutter used as the outer circle cutter in the drop bow compass of FIGURE 1.

FIGURE 5 is a still further enlarged front elevation of the chisel type cutter taken substantially tangential to the path of the outer circle chisel type cutter.

FIGURE 6 is an elevaion of a concentric circle scribing device.

FIGURE 7 in a vertical section through the slidable center of the circle scribing device of FIGURE 6 in place on a scribe coated film showing the operative position of the scribing elements with relation to a scribable coating shown on a fragment of film.

FIGURE 8 shows the circle scribing device of FIG- URES 6 and 7 with the parts held with the scribing elements retracted manually from the center point to facilitate locating the center on a scribe coated film.

Referring more particularly to FIGURES l-5 of the drawings, a circular peel coat cutting device to produce concentric slits in a peelable coating includes a drop center type of compass. The drop center compass includes a tubular sleeve body extending downwardly from a mounting block 61 with an internally threaded tubular extension 62 projecting upwardly from the mounting block 61. A center rod 63 extends through the tube 60, block 61 and extension 62 having a sharpened projecting point center 64 at one end and a finger engaging knurled knob 65 at the other end. An adjustable stop 66 in the form of a collar with a set screw 66A limits the downward movement of the center rod 63 against a tubular abutment sleeve 67A removably secured by threaded engagement in the upper threaded end of extension 62. A knurled flange 67B provides .for removal of threaded abutment sleeve 67A and also serves as an additional means to rotate the instrument. A tubular stop 67 located in the tubular extension 62 is fixed to the center rod 63 by any suitable means such as shrinking thereon and limits the upward movement of the center rod while permitting disassembly. Adjustment of the stop 67 can be obtained by reversing the shrinking process and changing the position of stop 67 or by a strong force in a press or the like.

A tubular cutter 68 is provided with an upper knurled portion 69 having an annular internal groove 70 communicating with the major bore 71 and such annular groove 70 receives a split resilient ring 72 adapted to yieldably and frictionally grip the center rod 63 and maintain the tubular cutter 68 in position on the rod 63. The lower end of the rod 63 is reduced in diameter in the portion 73 and a cooperating reduced bore 74 in the tubular cutter 68 maintains the tubular cutter in radial position with respect to the center rod 63. The lower end of the tubular cutter 68 is provided with a sharpened edge 75 which may be obtained by providing a conical end on the tubular cutter 68 and then sharpening the conical end of cutter 68 in the form of a flattened cone having its axis 75A askew to the axis of the tubular cutter 68 thereby producing the cutting edge 75 substantially tangent to a circle of the radius between center point 64 of the rod and the cutting edge 75, the lowest point of the cutting edge doing the actual cutting.

It will be noted that the stop 67 is so arranged that it will engage the lower end of the threaded sleeve 67A in such a position that the upper end of the tubular cutter 68 (FIG. 3) will engage the lower end of the tube 60 to locate the center point 64 of the rod 63 just above the lowest point of the cutting edge 75 of the tubular cutter 68 when center rod is raised to its maximum withdrawn position. It will also be evident that the tubular cutter 68 is kept in guiding relation by the bore 71 and split ring 72 engaging rod 63 and by the reduced bore 74 engaging the reduced portion 73 of the center rod. Rotation of the rod 63 by means of the knob 65 will cause the tubular cutter 68 to rotate while the center point 64 of the rod maintains the rod on the selected center on the work and the cutting edge 75 makes a small circular cut in the peelable coating. The split ring is of such shape as to cause frictional and resilient engagement between rod 64, spring 72 and groove 70. It will also be evident that the center rod 63 may be held with the center point 64 at the selected center of the work such as at the location of a circuit pad and the tubular cutter 68 rotated by engagement of a persons thumb and finger with the upper enlarged knurled portion 69 of the tubular cutter.

The outer circle of the circuit pad is slit by a chisel type cutter 76 having a generally chisel-shaped cutting extremity formed by the dihedral surfaces 77 which converge at a cutting edge or point 78 and such cutting point 78 is defined by the intersection of two pairs of dihedral surfaces 79 with the lines defined by each pair of dihedral surfaces 79 intersecting at the cutting edge or point 78.

This chisel type cutter 76 is secured in the usual pencil lead clamp 80 by means of an adjusting clamp screw 81 mounted on a stem 82 secured in a socket in a block 83 by means of a nut 84 threaded onto a stud 85 which stud also secures the block 83 to one leaf spring 85 secured to the main block 61 by a screw (not shown). Another leaf spring 86 secured to the main block 61 by a screw 88A and to the pen or pencil attaching block 83 serves to maintain the pencil receiving block 83 in generally parallel relation to maintain the cutter 76 in substantially parallel relation to its initial cutting position to assure uniform cutting action. The adjustment between the center point 64 and the cutting point 78 is obtained by a knurl head radial adjustment screw 87 threaded into an externally and internally threaded flanged tubular nut 88 which nut 88 secures one end of the leaf spring 86 to the pen and pencil receiving block 83, the other end of the leaf 86 being secured in position by the screw 88A and the upper end of the spring 85 being secured by a suitable machine screw threaded into the block 61 (not shown).

In use the concentric circle circuit pad slitting device of FIGURES 1-5, inclusive, may be adjusted to the external radius of the pad by the setting of the distance between center point 64 and chisel-like cutting point 78 and the rod 63 withdrawn to its uppermost position as shown in FIGURE 3 to locate the point 64 within the bore 74 and spaced upwardly from the cutting point 75. The concentric circle slitting device is located with the cutting point 75 in its correct position on the peelable coat 31 with the rod 63 perpendicular. Pressure is applied downwardly on knob 65 causing center point 64 to penetrate the peel coat and such pressure is transferred to tubular cutter 68 through spring 72 and by rotation of the rod 63 by means of knob 65 the cutting edge 75 is moved through at least 360 to make a complete cut while the center point 64 is retained in position. The friction and resiliency of the split ring 72 provides a clamping action between the rod 63 and the tubular cutter 68 maintaining suflicient downward force on the cutting point 75 to produce the necessary cutting of the center circle.

Thereafter the rod 63 is maintained in a perpendicular position by one hand and the operator rotates the adjustable arm of the device by engagement with the knurled portion of tubular extension 62 and/ or tubular stop screw 67A with sufiicient downward force on the cutting point 78 to obtain a cutting action and after a complete rotation at the required cutting pressure the circuit pad is outlined with a slit extending completely through the peelable coat.

It will be understood that the slitting of the peelable coat with cutter 76 through cutting point 78 may be discontinuous through the peelable coat so that the portion of the peelable coat corresponding to the circuit pad adjacent to the portion of the peelable coat corresponding to the conductive lead may remain connected to permit peeling of the entire circuit pad and conductive lead area in one operation.

Referring to FIGURES 6 to 8, inclusive, a concentric circle scribing device is shown to include a vertically disposed cylindrical body having an axial bore 101 extending therethrough and receiving a tubular cutter 102 having a flange 103 at its upper end and a cutting edge 104 at its lower end, said tubular cutter being of greater length than the body to project from both ends thereof. An elongated cutter 105 is vertically adjustably mounted in a vertically extending opening 106 and secured in adjusted position by a set screw 107 so that the lower sharpened end 108 will extend downwardly beyond the lower end of body 100. An open bottom cylindrical cap 109 provided with internal threads at its open end is received on external threads 110 on an enlargement at the upper end of the body 100, the upper end of the cap 109 being closed and provided with a boss 111 having an axial bore therethrough in alignment with and of the diameter of the central bore .of the tubular cutter 102, the bores of said boss 111 and of said tubular cutter 102 receiving a center shaft 112 for relative axial and rotatable movement. The center shaft 112 is provided with a finger engaging knurled knob 113 at its upper end and with a sharpened conical point 114 at its lower end. An abutment plate 115 is positioned within the cap 109 and has a passage receiving the center shaft 112 and is secured to e such center shaft by a set screw 116 to prevent relative axial movement between the abutment plate 115 and the shaft 112. An aperture 117 is provided in the side of the cap 109 to provide access to the set screw 116. A first compression spring 118 positioned within the cap 109 has its upper end received in a groove in the abutment plate 115 and its lower end received in a groove in the upper end of the body 100 whereby the abutment plate 115 with the center shaft 112 is normally urged upwardly to a position in which the center point 114 lies above the normal position of the cutting points 104 and 108. A second compression spring 119 surrounding the center shaft 112 abuts the flange 103 of the center tubular cutter 102 and the abutment plate 115 thereby normally urging the tubular cutter 102 to its projected position shown in FIG. 8. A keying pin 120 fixed in an upwardly opening aperture in the body 100 extends through an enlarged aperture in the flange 103 preventing relative rotation of the tubular cutter 101 with respect to the body 100 while permitting relative axial movement.

In use the circular scribing device of FIGURES 6 to 8 is manipulated by the operator so that the cap 109 is drawn upwardly on center shaft 112 so the boss 111 abuts the hub of the knob 113 thereby causing the point 114 of the device to project beyond the scribing points of Cutters 104 and 108 so that the operator can accurately locate the center 114 about which the circles are to be scribed and after the point is located the operator releases the cap 109 and such cap 109 with the body 100 moves toward the material to be scribed as shown in FIGURE 6 until the scribing point 108 engages the surface 121 to be scribed. The tubular scribing device 102 is also urged downwardly by the action of the spring 119 so that scribing point 104 engages the surface 121 to be scribed, the operator applying suificient downward pressure on the knob 113 to maintain the center point on the center about which the circles are to be scribed and the scribing points 108 and 104 will remain in contact with the surface 121 due to the spring pressure and then the operator rotates the scribing device by engagement of the fingers with the knurled surface of the cap 109 and concentric circles are scribed by the points 104 and 108.

It will be evident from observing the position of the parts in FIGURE 7 that the cutting point 104 can be made to engage the surface prior to the engagement of the surface by cutting point 108 and a complete circle may be made by the inner cutter if the operator takes care to prevent the cutter 108 from contacting the work and a partial circle may be drawn with the outer cutter 108 if desired to avoid crossing scribed lines such as at locations where circuit pad outlines join conductor lead outlines.

It will be apparent that various changes may be made within the spirit and scope of the invention within the valid interpretation of the claims.

What is claimed is:

1. A scribing device comprising a drop center compass having a tubular drop center support, a pointed drop center shaft in said tubular support, means to limit axial movement of said drop center shaft, a scribing arm adjustably mounted on said tubular drop center support, a V-edge chisel cutter on the scribing arm, a tubular cutter embracing the point end of the drop center shaft and having a sharpened edge spaced from the axis of said cutter, resilient means frictionally maintaining said tubular cutter on said drop center and providing sufficient resistance to axial movement to cause cutting of the cutting edge thereof upon contact of the cutting edge of said tubular cutter and of the point of the drop center with a cuttable material whereby upon rotation of said drop center and/or said tubular cutter an inner circle of material will be cut, said chisel cutter producing an outer circle cut upon rotation of said compass about said point.

2. The invention according to claim 1 in which the limit means positions the sharpened edge of said tubular cutter in a definite position with respect to said drop center point when said drop center shaft is moved axially in a direction away from the point.

3. The invention according to claim 2 in which the limit position of the withdrawn drop center relative to the tubular cutter to cut and thereafter the scribing arm may scribed so that rotation of the drop center causes said tubular cutter to cut and thereafter the scribing arm may be rotated to obtain a cutting action by said chisel-pointed edges thereof.

4. The invention according to claim 1 in which the tubular cutter is provided with an internal groove and a split ring spring is positioned therein to obtain sufficient friction between said tubular cutter and said drop center to retain the parts in operative relation.

5. A scribing device comprising a drop center compass having a tubular drop center support, a pointed drop center shaft in said tubular support, means to limit axial movement of said drop center shaft, a scribing arm adjustably mounted on said tubular drop center support, a first scriber on the scribing arm, a second scriber embracing the point end of the drop center shaft and having a scribing point spaced from the axis of said second cutter, yieldable means maintaining said second scriber on said drop center and providing sufficient resistance to axial movement to cause scribing by the scribing point of said second scriber upon contact of the scribing point of said second scriber and of the point of the drop center shaft with a scribable material whereby upon rotation of said drop center and/ or said second scriber an inner circle of material will be scribed, said scribing point of said first scriber producing an outer circle upon rotation of said compass about said center point.

6. A scribing device comprising a compass having a body and a center shaft with a center point projecting from said body to contact a supporting surface at the center point of arcs of different radii to be scribed, said compass also having a radially extending portion, a scribing point spaced radially from said center shaft and mounted on said radially extending portion to scribe an arc of appreciable radius, a scriber cutter having a tubular shank embracing said center shaft and having a single scribing edge at one point extending beyond the shank, said scribing cutter being mounted on said center shaft for movement axially thereof, yieldable means to retain said scribing cutter in position whereby said scribing edge may engage a surface supporting said center point to scribe an arc of small radius or may be movable out of scribing contact with the supporting surface.

7. The invention according to claim 6 in which the compass includes a body and the center shaft is axially movable relative to the body and the scriber cutter is relatively movable axially with respect to said center shaft and body.

8. The invention according to claim 6 in which the body has an axial bore extending therethrough, the tubular scriber cutter being mounted in said axial bore, the center shaft being mounted in the shank, spring means urging said center shaft toward said body, and spring means urging said tubular scriber cutter in the direction away from said body.

9. The invention according to claim 8 in which the body is of cylindrical shape and the scribing point spaced radially from said center shaft is secured to said body of cylindrical shape and projects therefrom a distance greater than the retracted positions of said center shaft and said tubular scriber cutter whereby the center point of the center shaft, the scribing edge of the scriber cutter with the tubular shank and the scribing point may all contact the supporting surface to simultaneously scribe large and small arcs.

10. The invention according to claim 6 in which the body is an elongated tubular sleeve, the center shaft being mounted for axial movement within said tubular sleeve and the scriber cutter having a tubular shank being mounted on the pointed end portion of the center shaft projecting from said tubular sleeve body.

11. The invention according to claim 10 in which stop means are provided between said tubular sleeve body and said center shaft to limit relative axial movement and the yieldable means to retain the scribing cutter with a tubular shank in position is a resilient split ring retained within a groove in the inner periphery of the tubular shank of the scribing cutter.

References Cited UNITED STATES PATENTS 2,368,908 2/1945 Witter et a1 30-310 X HARRY N. HAROIAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,394 ,460 July 30, 1968 Charles H Stein et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 40, cancel "tubular cutter to cut and thereafter the scribing arm may" and insert tubular cutter provides for contact of a surface being Signed and sealed this 30th day of December 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr. Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

